Tyre with improved edge protection of a belt ply oriented substantially in the circumferential direction of the tyre

Abstract

The present invention relates to a pneumatic tyre having a carcass layer (11), a belt layer (15, 16, 13) which is arranged on the outside of the carcass layer, and a tread rubber which is arranged on the outside in the tyre radial layer in the belt layer, wherein the belt layer has a circumferential reinforcement layer (14) which is embedded between other belt plies and has a belt angle within a range of ± 5° with respect to the circumferential direction of the tyre, and wherein the circumferential reinforcement layer is formed by steel cords, characterised in that the pneumatic tyre has, in the region of the ends of the circumferential reinforcement layer, a rubber strip ply (17) which is positioned directly above and / or directly below the circumferential reinforcement layer and which is attached at least in a width region of the tyre at which one or more ends of cords of the circumferential reinforcement layer are present. The inserted rubber strip ply prevents direct contact between belt plies positioned above and below the circumferential reinforcement layer and leads to improved tyre durability.

Description

[0001] 202405966

[0002] 1

[0003] Description

[0004] Tires with improved edge protection of a belt layer oriented essentially in the direction of the tire's circumference

[0005] The present invention relates to a pneumatic tire comprising a carcass layer, a belt layer arranged on the outside of the carcass layer, and a tread rubber arranged on the outside in the radial layer of the belt layer, wherein the belt layer has a circumferential reinforcement layer embedded between other belt layers, the belt angle having a belt angle within a range of ± 5° with respect to the tire's circumferential direction, and wherein the circumferential reinforcement layer is formed by steel cords, characterized in that the pneumatic tire has a rubber strip layer in the region of the ends of the circumferential reinforcement layer, the strip being positioned directly above and / or directly below the circumferential reinforcement layer and extending over at least a width region of the tire, where one or more ends of cords of the circumferential reinforcement layer are present.

[0006] State of the art

[0007] To achieve increased strength, an optimized contact patch, and improved tire life and retreadability, it is known that a belt layer made of an endless steel cable can be integrated into the tire. Tires constructed in this way play a significant role, particularly in heavy-duty applications. Since these belt layers, which are typically oriented at an angle of 0 to 5° to the tire's equator, are usually narrower than the other belt layers in the tire, they are subject to considerable stress at their edges.

[0008] To reduce fatigue fractures in the edge region of the belt layer caused by these loads, EP 2033814 B1 describes the insertion of a “load reduction layer” adjacent to the ends of the 202405966

[0009] 2

[0010] The tire disclosed in EP 2033814 B1 has an edge buffer layer arranged on the side of the load-dissipation layer opposite the edge of the circumferential reinforcement layer and extending to the edges of the belt layers positioned above the circumferential reinforcement layer.

[0011] German patent DE 112014002101 B4 describes a pneumatic tire for heavy-duty applications in which the distances between the cords of the circumferential reinforcement layer and the cords of the belt layers above and below it are greater at the tire equator than at the edges of the circumferential reinforcement layer, for example, by incorporating larger quantities of rubber in this area. This is intended to achieve improved uniformity of radial expansion and thus improved tire durability.

[0012] EP 4227113 A1 describes tires for heavy-duty applications that can be constructed with fewer belt plies, thus achieving a lower weight than conventional tires. In the edge region of the belt plies, a rubber layer can be arranged in EP 4227113 A1, which can also fill the space between the ends of a belt ply with an orientation of the belt cords in the range of 0 to 5° with respect to the tire equator and the belt plies positioned above and below it.

[0013] One problem with the design of the circumferential reinforcement layer lies in the production time, as a very long steel cord must be continuously wound around the raw tire to create the belt layer. While this process can be accelerated by wrapping two or more parallel steel cords around the raw tire instead of one, this results in larger areas at the beginning and end of the winding process that are not covered by steel cords because the cords end there. Consequently, less material is present in these areas during regular tire production, which increases the susceptibility to defects.

[0014] 3. This can lead to cords from the belt layers above and below the circumferential reinforcement layer touching in this area. If these belt layers exhibit significant deviations in their orientation, this results in excessive stress and wear in the areas in question.

[0015] One possible solution to this problem is to add extra rubber specifically to the beginnings and ends of the cords in the circumferential reinforcement layer, but this is difficult to integrate into an accelerated manufacturing process. Against this background, there is a need for pneumatic tires that can be manufactured quickly and therefore more cost-effectively, and which, particularly when the circumferential reinforcement layer consists of more than one cord, exhibit improved durability of the load-bearing belt layers in the edge area of ​​the belts.

[0016] Description

[0017] The investigations underlying this invention revealed that by partially covering the circumferential reinforcement layer with a rubber overlay that completely covers the area where the ends of the cords of the circumferential reinforcement layer are located, a sufficient amount of material can be incorporated to prevent direct contact between cords of work belt layers in these areas. The use of a rubber overlay applied to the entire circumference of the tire has the advantage that this step can be carried out on one side of the tire while the tire cords are still being wound onto the tire body, and the overlay can be applied to the other side without having to determine beforehand the position of the cord ends of the circumferential reinforcement layer.Another manufacturing option is to apply the rubber pad to the belt during the preparation phase, eliminating the need to apply an additional strip to the construction machine. This method is described in part number 202405966.

[0018] Four such tires simplify the process compared to applying rubber only at the critical ends of the cords.

[0019] The present invention therefore relates to a pneumatic tire comprising a carcass layer, a belt layer arranged on the outside of the carcass layer, and a tread rubber arranged on the outside in the radial layer of the belt layer, wherein the belt layer has a circumferential reinforcement layer embedded between other belt layers, the belt angle having a belt angle within a range of ± 5° with respect to the tire's circumferential direction, and wherein the circumferential reinforcement layer is formed by steel cords. This pneumatic tire has a rubber strip layer in the region of the ends of the circumferential reinforcement layer, which is positioned directly above and / or directly below the circumferential reinforcement layer and is applied over at least a width region of the tire where one or more ends of cords of the circumferential reinforcement layer are present.

[0020] The specification "width area of ​​the tire where one or more ends of cords of the circumferential reinforcement layer are located" in relation to the positioning of the rubber strip ply is to be understood as meaning that the ends of the cords of the circumferential reinforcement layer are covered "from above and / or below" by the rubber strip ply, i.e., the rubber strip ply is positioned in this area between the circumferential reinforcement layer and a belt ply located above or below it. The term "rubber strip ply" indicates the fact that this rubber ply, unlike, for example, thin rubber plies in which the cords of belt plies located above and / or below the circumferential reinforcement layer are embedded, does not extend completely across the entire width of the belt plies (i.e.,Particularly in the area of ​​the tire equator, the circumferential reinforcement layer is not covered by the rubber strip layer, and the rubber strip layer is also not located beneath the circumferential reinforcement layer in this area. 202405966.

[0021] 5

[0022] The term "directly above and / or directly below" refers to the fact that no other belt layers are located between the circumferential reinforcement layer and the rubber strip layer in this area, and that no other materials are located between the belt layer adjacent to the circumferential reinforcement layer and the rubber strip layer in this area. However, this does not preclude the circumferential reinforcement layer and / or the adjacent belt layer itself from containing rubber material in addition to the belt cords, in which the belt cords are embedded.

[0023] As mentioned above, it is advantageous for faster production of pneumatic tires according to the invention if the circumferential reinforcement layer is formed from two or more steel cords that are aligned parallel to each other for winding onto the tire. Accordingly, pneumatic tires in which the circumferential reinforcement layer is formed from at least two parallel steel cords that are wound onto the tire simultaneously during construction are preferred; a circumferential reinforcement layer formed from three parallel steel cords is even more preferred. A higher number of steel cords, however, is less advantageous because the tire becomes less uniform in shape with such a construction, which is no longer offset by the additional time saved by the higher number of steel cords in the manufacturing process.

[0024] The rubber material from which the rubber strip layer is made is not subject to any relevant restrictions in the context of the pneumatic tires described here according to the invention, although the properties of the material can usually be based on the properties of other rubber materials used in pneumatic tires. In this context, the term "rubber material" refers to a rubber compound which, in addition to rubber components, may contain additives commonly used in tire rubber compounds, particularly in the form of fillers such as carbon black or silicon dioxide.

[0025] A rubber material particularly suitable for the rubber strip layer in the context of the present invention has a storage modulus E' at 55° according to DIN 53513-202405966

[0026] 6

[0027] 1990 within a range of 12 to 17 MPa, and preferably 13 to 16 MPa. Additionally or alternatively, it is preferred that the rubber strip layer has an elongation at break X according to DIN 53304-1977 at RT of not less than 380%, and particularly in the range of 430% to 600%.

[0028] There are no relevant restrictions on the extension of the rubber strip layer towards the tire's equator. However, it should be noted that a wider rubber strip layer requires more material and increases the weight of the resulting tire, without any corresponding advantages. Therefore, it is advisable that the rubber strip layer does not extend significantly beyond the area of ​​the circumferential reinforcement layer where the ends of the belt cords of this layer are positioned. An extension of the rubber strip layer over a maximum of 10% of the total width of the circumferential reinforcement layer can be considered suitable (with rubber strip layers on both sides of the tire's equator, this results in a maximum coverage of 20% of the total width of the circumferential reinforcement layer).It is particularly preferred if the rubber strip layers extend from the ends of the circumferential reinforcement layer towards the tire equator over a maximum of 5% of the total width of the circumferential reinforcement layer. An overlap of the widest point of the circumferential reinforcement layer and the rubber strip layer is expediently 5 mm, preferably 10 mm, on each side.

[0029] The overall width of the rubber strip ply can be adjusted by a specialist depending on the tire dimensions, the width of the circumferential reinforcement layer, the width of the cross plies, and the desired extension of the rubber strip ply towards the tire shoulder. A width in the range of 15 to 60 mm, and especially 20 to 40 mm, is considered particularly suitable. A suitable thickness for the rubber strip ply is in the range of 0.4 to 2 mm, and especially 0.8 to 1.5 mm.

[0030] In a vulcanized pneumatic tire, determining and delineating a layer of rubber strips can be difficult if it is made of a single material. 202405966

[0031] 7 is indistinguishable from the material used in other belt layers. On the other hand, the inclusion of the rubber strip layer increases the amount of material in the area of ​​the edge of the circumferential reinforcement layer, which generally also results in a greater thickness of the rubber between the cord threads of the circumferential reinforcement layer and the belt layers between which it is embedded. The respective rubber thicknesses at the tire equator can be used as a reference for defining a "greater thickness".

[0032] For the pneumatic tires according to the invention, it is preferred that the distances between the cord threads of the circumferential reinforcement layer and the cord threads of the belt layer dso positioned above the circumferential reinforcement layer, and the cord threads of the belt layer dsu below it in the end region of the circumferential reinforcement layer, and the distances between the cord threads of the circumferential reinforcement layer and the cord threads of the belt layer dco positioned above the circumferential reinforcement layer, and the cord threads of the belt layer dcu below it at the tire equator, are in a ratio to each other such that (dco+dcu) / (dso+dsu)<1.2. It is further preferred that (dco+dcu) / (dso+dsu)<1.0, so that the sum of the distances in the end region of the circumferential reinforcement layer dso+dsu is greater than at the tire equator. For a better illustration of the distances, reference is made to Figure 2.As shown in Figure 2, the respective distances are to be determined by laying a line through the upper and lower intersection points of the cord threads with rubber material of a belt layer and determining the distance between the upper line of one belt layer and the lower line of the belt layer above it.

[0033] Since the inclusion of rubber strip layers according to the invention particularly avoids wear caused by the direct contact of belt layers with significantly different belt angle orientations, and such layers in heavy-duty tires are usually present in the form of belts with angles of opposite signs (also referred to as "cross belts"), it is further preferred if belt layers with a belt angle in the range of 10 to 45° and with a 202405966

[0034] 8

[0035] The belts are arranged in an orientation opposite to the tire's equator. In this configuration, the advantages offered by the rubber strip layers are most clearly evident. Belt layers in which the belt cords are oriented at an angle of 10 to 45° and in opposite directions to each other are also referred to as "working belt layers".

[0036] For the pneumatic tires according to the invention, it is further advantageous if the belt layers, between which the circumferential reinforcement layer and the rubber strip layer are arranged, extend further towards the tire shoulder than the circumferential reinforcement layer, and if the rubber strip layer extends at least to the edge of this belt layer in the direction of the tire shoulder. Such a design ensures that the belt layer arranged above the circumferential reinforcement layer is not subjected to any significant deformations in the area of ​​the ends of the circumferential reinforcement layer, particularly if these areas are not filled with another rubber material. For such a design, it may be expedient if the rubber strip layer extends around the edge of the belt layer and over a portion of the side of the belt layer facing away from the circumferential reinforcement layer.In this way, the rubber strip layer can be used as edge protection, wrapped around the edges of the belt.

[0037] In a further advantageous embodiment of the pneumatic tire according to the invention, a belt edge pad is provided between the ends of the circumferential reinforcement layer and the tire shoulder. In this case, the rubber strip layers are arranged above, below, or both above and below the belt edge pad.

[0038] The inventive design of pneumatic tires with rubber strip layers is particularly suitable for pneumatic tires used in heavy-duty applications. Since such tires generally have rather low aspect ratios (i.e., a comparatively large width), it is preferred if the pneumatic tire according to the invention has an aspect ratio of 70% or less, and particularly 60% or less. 202405966

[0039] 9

[0040] In a further aspect, the present invention relates to a method for manufacturing a pneumatic tire as described above, wherein the method comprises the following steps: i) providing a carcass package, ii) applying at least one belt layer to the carcass package, iii) applying a circumferential reinforcement layer by winding on at least one belt cord in such a way that the belt cord(s) are oriented at an angle in the range of 0 to 5° to the tire's equatorial plane, iv) applying a rubber strip layer directly below and / or directly above the edge regions of the circumferential reinforcement layer in such a way that the rubber strip layer is applied in a width region of the tire where one or more ends of cords of the circumferential reinforcement layer are present, v) applying at least one further belt layer and at least one further rubber pad.and iv) vulcanizing the pneumatic tire in a mold to form a composite of carcass package, belt plies, rubber strip plies and rubber liner.

[0041] Within the framework of the specified procedure, further components, such as belt edge padding or

[0042] Sidewall cushions are incorporated into the tires.

[0043] In a further aspect, the present invention relates to a pneumatic tire which was manufactured or can be manufactured according to a method as described above.

[0044] Finally, a further aspect of the present invention relates to a vehicle, in particular in the form of a truck or bus, which is equipped with at least one pneumatic tire as described above. 202405966

[0045] 10

[0046] The present invention will now be explained in more detail with reference to the schematic tire construction shown in Figure 1. Figure 1 shows a section of a pneumatic tire 10 with a carcass layer 11 and further belt layers 15 and 16 arranged above it. Belt layer 15 is a working belt layer, which can, for example, be formed with a belt angle to the circumferential reinforcement layer in the range of +10° to 45°. A circumferential reinforcement layer 14 is arranged above this. Above this is another working belt layer 13, which can, for example, be formed with a belt angle to the circumferential reinforcement layer in the range of -10° to -45°. In Figure 1, a further belt layer 12 is also present above this further working belt layer, which together with the other belt layers forms the belt stack of the tire.The working belt layers 13 and 15 extend significantly further towards the tire shoulder than the circumferential reinforcement layer.

[0047] The pneumatic tire shown in Figure 1 has, in addition to the belt plies, a belt edge pad 18, which is formed in the area between the end region of the circumferential reinforcement layer 14A and the working belt plies 13 and 15, as well as a side edge pad 20, which is formed in the area below the belt plies 15 and 16 and above the carcass layer 11. Towards the tire shoulder, this is covered by the sidewall rubber of the tire.

[0048] In the tire shown in Figure 1, 21 denotes a main circumferential groove of the tire. The tire also has a rubber strip layer 17, positioned between the circumferential reinforcement layer 14 and the work belt layer 13. The rubber strip layer 17 covers part of the end region of the circumferential reinforcement layer and extends from there to the end of the work belt layer 13, partially extending beyond the end of the work belt layer 13 onto its upper surface, thus forming a sandwich structure with the work belt layer in this area. 202405966

[0049] 11

[0050] Reference symbol list

[0051] 10 pneumatic tires

[0052] 11 Carcass layer 12 Upper belt layer

[0053] 13 Upper working belt position

[0054] 14. Circumferential reinforcement layer

[0055] 14A End area of ​​the circumferential reinforcement layer

[0056] 15 Lower working belt position 16 Further belt position

[0057] 17 rubber strip layers

[0058] 18 belt edge pads

[0059] 19 tire shoulder

[0060] 20 Side edge padding 21 Main circumferential groove

Claims

202405966 12 Patent claims 1. Pneumatic tire comprising a carcass layer, a belt layer arranged on the outside of the carcass layer, and a tread rubber arranged on the outside in the radial layer of the belt layer, wherein the belt layer has a circumferential reinforcement layer embedded between other belt layers, having a belt angle within a range of ± 5° with respect to the tire's circumferential direction, and wherein the circumferential reinforcement layer is formed by steel cords, characterized in that the pneumatic tire has a rubber strip layer in the region of the ends of the circumferential reinforcement layer, which is positioned directly above and / or directly below the circumferential reinforcement layer and which is attached in at least a width region of the tire where one or more ends of cords of the circumferential reinforcement layer are present.

2. Pneumatic tire according to claim 1, wherein the circumferential reinforcement layer is formed from at least two, preferably three parallel steel cords which are wound onto the tire simultaneously as part of the construction.

3. Pneumatic tire according to claim 1 or 2, wherein the rubber strip layer has a storage modulus E' at 55° according to DIN 53513-1990 within a range of 12 to 17 MPa, and preferably 13 to 16 MPa.

4. Pneumatic tires according to at least one of claims 1 to 3, wherein the rubber strip layer has an elongation at break X according to DIN 53304-1977 at RT of not less than 380%, and in particular in the range of 430% to 600%.

5. Pneumatic tires according to at least one of the preceding claims, wherein the rubber strip layers extend from the ends of the circumferential reinforcement layer over a maximum of 10% of the total width of the circumferential reinforcement layer in the direction of the tire equator, 202405966 13 preferably over a maximum of 5% of the total width of the circumferential reinforcement layer.

6. Pneumatic tires according to at least one of the preceding claims, wherein the rubber strip layers have an overlap with the widest point of the circumferential reinforcement layer on each side of 5 mm, preferably 10 mm.

7. Pneumatic tires according to at least one of the preceding claims, wherein the rubber strip layer has a width in the range of 15 to 60 mm and preferably 20 to 40 mm and / or a thickness in the range of 0.4 to 2 mm, preferably 0.8 to 1.5 mm.

8. Pneumatic tire according to at least one of the preceding claims, wherein the distance between the cord threads of the belt layers embedding the circumferential reinforcement layer and the circumferential reinforcement layer d at the end of the circumferential reinforcement layer dso, dsu and at the tire equator dco, dcu are in a ratio to each other such that (dco+dcu) / (dso+dsu)<1 ,2, preferably (dco+dcu) / (dso+dsu)<1 ,0.

9. Pneumatic tires according to at least one of the preceding claims, wherein belt layers with a belt angle in the range of 10 to 45° and with an orientation opposite to the tire equator are arranged above and below the circumferential reinforcement layer.

10. Pneumatic tire according to at least one of the preceding claims, wherein the belt layer, between which the rubber strip layer is attached and the circumferential reinforcement layer, extends further in the direction of the tire shoulder than the circumferential reinforcement layer and wherein the rubber strip layer extends at least to the edge of this belt layer in the direction of the tire shoulder. 202405966 14 11. Pneumatic tire according to claim 10, wherein the rubber strip layer extends around the edge of the belt layer and over a part of the side of the belt layer facing away from the circumferential reinforcement layer.

12. Pneumatic tire according to at least one of the preceding claims, wherein a belt edge pad is provided between the ends of the circumferential reinforcement layer and the tire shoulder, and the rubber strip layer is applied above, below or both above and below the belt edge pad.

13. Pneumatic tire according to at least one of the preceding claims, wherein the pneumatic tire has an aspect ratio of 70% or less and in particular 60% or less.

14. A method for manufacturing a pneumatic tire according to any one of claims 1 to 13, comprising providing a carcass package, applying at least one belt layer to the carcass package, applying a circumferential reinforcement layer by winding on at least one belt cord in such a way that the belt cord(s) are aligned at an angle of 0 to 5° to the tire's equatorial plane, applying a rubber strip layer directly below and / or directly above the edge regions of the circumferential reinforcement layer in such a way that the rubber strip layer is applied in a width region of the tire where one or more ends of cords of the circumferential reinforcement layer are present, applying at least one further belt layer and at least one further rubber layer, and a final step of vulcanizing the pneumatic tire in a mold to form a composite of carcass package,Belt layers and rubber strip layers.

15. Vehicle, in particular in the form of a truck or bus, equipped with at least one pneumatic tire according to any one of claims 1 to 13.

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